In a dual controller storage system, there are two controllers which are referred to as storage processors to provide a storage service to a host. Usually, cache mirroring technology is employed to ensure security of data in the cache. The principle of the cache mirroring lies in mirroring the data in the caches between two storage processors, that is to say, the data in the caches of the two storage processors are backed up to each other. It is challenging to allocate an access right to the data in the caches among two or more storage processors to implement unified management of the storage system.